The present invention relates to a stepping motor for driving, for example, a timepiece or an electric fan.
In a related art, a stepping motor for a timepiece is known as a stepping motor which can be driven by a low current(refer to, for example, Patent Reference 1 and Patent Reference 2).
Patent Reference 1: JP-A-49-56109
Patent Reference 2: JP-A-50-145806
However, a stepping motor for a timepiece of a related art is constituted by: a coil wired to an iron core and having a rectangular outer shape; a coil yoke for leading a magnetic circuit from the coil to a rotor magnet; and the rotor magnet arranged to be opposed to the coil yoke, and constitutes unsymmetric shape relative to an rotating shaft fixed with the rotor magnet. Further, an outer shape of the coil yoke is obliged to enlarge due to low-current formation and there is a limit in reducing an occupied area thereof. Therefore, when the stepping motor is attached to a timepiece or the like, the coil yoke is obliged to attach thereto by being deviated to one space (one side), and other space (the other side) constitutes a dead space which is inefficient.
Further, when the stepping motor is used for driving an electric fan having a small moment of inertia, there is a drawback that a path for convecting air is blocked by the coil yoke or the like.